The main components of the transformer insulating paper is cellulose, the role of O2, moisture and temperature and other factors will cause depolymerization of cellulose, a long chain molecules break into short chain scission molecules, and get the resulting of H2O, CO and CO2. The degree of aging of insulating paper is proportional to the degree of depolymerization.

Therefore, transformer oil content of CO and CO2 to some extent reflects the aging degree of transformer insulation paper. In the field, we generally use gas chromatography

instrument measuring content of CO and CO2, this method is simple and reliable. Measuring the tensile strength of the insulation paper insulation paper may determine the extent of aging degree, if the insulating paper tensile strength is less than 50% of the initial value that it can be determined transformer aging has become very serious, and the transformer can be considered to quit running. Insulation paper tensile strength directly reflects the degree of aging of the transformer, but the measurement of tensile strength of insulating paper blackout hanging core premise is not easy to achieve in a production running, so as the case it suggested to be used for transformers which are used overhaul 10 years to 15 years.

Transformer on the same statistical models to calculate the average life of the transformer, with the calculation results to evaluate the aging and remaining life.

This method is simple to implement and low cost. However, for large-capacity main transformer AP1000, the first AP1000 has not yet put into operation, no transformer can refer to the same model, so this method can not be implemented.